The present invention relates to equipment, commonly referred to as xe2x80x9cfeedersxe2x80x9d, for dispensing finely divided particulate materials that are flowable. In particular this invention relates to an apparatus and a method for removing interstitial air between the particles of finely divided particulate materials while they are being dispensed through a feeder.
Many continuous processes that include adding finely divided particulate materials, such as silica, carbon black, and other fillers, are typically rate-limited by the volume addition of those materials. In part, this is because most finely divided particulate materials interstitial and entrained air, and have a large part of their volume represented by air. For this reason there have been attempts to remove the air by vacuum, and/or densify the finely divided particulate material by mechanical means such as shaking or compacting.
U.S. Pat. No. 3,664,385 to Carter teaches an apparatus and a method of compacting finely divided particulate material which uses a first rotating screw feeder for advancing the material along a housing having a tubular sleeve mounted within the housing. The sleeve and housing define a closed hollow chamber, extending about the sleeve with a plurality of perforations in the sleeve. Suction is applied chamber so that air can flow from the sleeve to the chamber. Intermittent air pressure is applied to the chamber to back-flush particulate material from the perforations. The particulate material, which is densified in the first rotating screw, is then mechanically advanced along the second sleeve passage to a container filling station.
The present invention is a feeder that removes interstitial air from finely divided particulate materials by creating a compression force counter to the material feed direction, allowing pressure to build up while the finely divided particulate material is transported through a housing and then venting air from the housing.